When you suffer from depression, it can feel like your own brain has betrayed you. That feeling may explain why the theory that depression is caused by a chemical imbalance in the brain is so widely believed to be true. Indeed, if depression can be reduced purely to anatomy, then perhaps it can be cured as easily as any other physical ailment. After all, who wouldn't want to take a magic pill that makes all of their suffering go away?
Now, a new study has undermined the aforementioned "serotonin hypothesis" — namely that, as the American Psychiatric Association puts it, "differences in certain chemicals in the brain may contribute to symptoms of depression." That hypothesis motivated the pharmaceutical industry's drug formulations, and indeed, underpins the chemistry of their anti-depressant drugs (particularly SSRIs, or selective serotonin-reuptake inhibitors), which were marketed to correct said imbalance. Neurologically speaking, these kinds of drugs perpetuate the presence of serotonin, a neurotransmitter with a wide variety of functions, in the brain; specifically, a "reuptake inhibitor" prevents the serotonin from being reabsorbed as quickly as it might naturally, meaning more of it circulates for longer.
